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Math

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What is the domain of

f(x) = √(x^2-2x-8)

Thanks!

  • Math - ,

    When the leading coefficient a is positive, the parabola opens up ( concave up )

    For function:

    x ^ 2 - 2 x - 8

    the leading coefficient is a = 1

    function is concave up

    When the parabola ia concawe up all walues between roots are negative.

    No negative number can have a real square root.

    Funtions zerro points are :

    - 2 and 4

    So domain of your fuction:

    ( - infinity , -2 ] U [ 4 ,infinity )

    OR

    x <= -2 and x >= 4


    If you don't knowe how to solve equation:

    x ^ 2 - 2 x - 8 = 0

    In google type:

    quadratic equation online

    When you see list of results click on:

    Free Online Quadratic Equation Solver:Solve by Quadratic Formula

    When page be open in rectangle type:

    x ^ 2 - 2 x - 8 = 0

    and click option: solve it!

    You wil see solution step-by-step


    If you want graph of functions:

    Go on :

    wolframalpha dot com

    When page be open in rectangle type :

    x ^ 2 - 2 x - 8

    and click option =

    after few seconds yo will everythig about function

    Then type :

    sqrt ( x ^ 2 - 2 x - 8 )

    and click option =


    P.S.

    Sorry for My bad English

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